Note that the potential function \({\Psi }\)  was proposed -in a more general form- in [1]}.
It is standard to show that \({\Psi }\)  is well-defined, e.g., see [1]}.
Later in our analysis we need to use certain results from [3]}, which (essentially) use
another, but related potential function from [4]}.
We postpone this discussion until later.
